Optical system for projecting the printed matter of typewriters



July 22, 1952 P. K. T. HARTMANN OPTICAL SYSTEM FOR PROJECTING THE PRINTED MATTER OF TYPEWRITERS 5 Sheets-Sheet 1 Filed Aug. 23, 1949 RTMHNN July 2 1952 Y P. K. 'r. HARTMANN OPTICAL SYSTEM FOR PROJECTING THE PRINTED MATTER OF TYPEWRITERS 5 Sheets-Sheet 2 Filed Aug. 23, 1949 INVENTOR.

N N m H T m R o a r H W T A K .S L U H DI Y B K. T. HARTMANN OPTICAL SYSTEM FOR PROJECTING THE July 22, 1952 P.

PRINTED MATTER OF TYPEWRITERS 3 Sheets-Sheet 3 Filed Aug. 25, 1949 INVENTOR. PHUL. K.'T HHRTMHNN g 41's ATTORNEY Patented July 22, 1952 UNITED" STATES serum OFFEE PRINTED MATTER OF TYPEWRITERS Paul K. "1. Hartmann, Woodhaven, N. Y.

Application August 23, 1949, Serial No. 111,818 g This invention relates to optical systems in general for projecting machines, and more especially to optical systems for projecting news items or printed matter as it is being printed by a machine, such as a manually or electrically operated typewriter.

Among the objects of the present invention it is aimed to provide an improved optical system for a projecting machine, and more particularly for projecting the images of printed matter on a tape as it is being printed by a machine such as an electric typewriter.

With electric typewriters, one of the difficulties encountered in projecting images of the printed matter as it is being printed results from the fact that the lines of printed matter on the tape or sheet while crossing a platen are comparatively inaccessible. .As an instance, although unusually excellent results have been obtained when the light rays are transmitted through the tape or sheet to form. images of the printed matter on the tape, it is very difficult and rather impractical to so position the tape after receiving the printed matter that light rays can pass through the same.

On the other hand, it has been found that when the light rays can pass through the tape, even though the images formed are then received by a mirror and reflected from a mirror onto a screen or onto other mirrors before passing to the screen, the images so produced are perfectly satisfactory.

In view of the foregoing, it is an object of the present invention to take advantage of this reflecting effect, by forming a plate with a reflecting surface to receive the tape as it is being printed, and to use such reflecting surface to cooperate with the light rays initially to receive the images formed when the light passes through the tape onto the reflecting surface and'then reflect them back through the tape either directly onto a screen or onto other mirrors or deflectors before passing the images so formed onto the screen.

These and other features, capabilities and advantages of the invention will appear from the subjoined detailed description of specific embodiments of the invention illustrated in the accompanying drawings, in which:

Fig. 1 is a side elevation showing the mechanism according to one embodiment and outlining the path of light rays from the lamp through two mirrors onto the front face of a front for a front projection screen as shown in Fig. 1

4 Claims. (Cl. 88--'24).

of a third embodiment using a spherical reflector instead of a parabolical reflector as shown-in Fig.1.

Fig. 6 is a side elevation partly broken away for a front projection screen as shown in Fig. 1 of a fourth embodiment using an elliptical-reflector instead of a parabolical reflector as shown. in Fig. 1. I

In the embodiment'illustrated in'Figs. 1, 2 and 3, there is shown a standard I in the present instance provided with legs 2 having rollers or casters 3 to enable moving the same from'place to place. The standard I has avertical extension t adjustably mounted therein having a racks in mesh with the gear 6 fixed on the shaft its journalled in the boss 1 of the standard i, on which the shaft l 05 is also fixed, the wormwheel lit being in mesh with the worm 8 mounted-on the shaft 9 extending outwardly of the boss 7 and having secured thereto the hand wheel it for actuating the worm wheel I I6 and in turn the extension 4 to the desired altitude withrespect to the mechanism now to be described;

At the upper end of the extension 4 there is secured the bracket H having the set scrwlZ extending therethrough to engage the extension and anchor the bracket 1 to theextension i. The bracket H in turn has a bifurcated portion it provided with binding screws i l to clamp the bifurcated extension l3, around the end ,ofthe shaft IS. The shaft 15' in turn has mounted thereon theboss it secured tothe rod ,l 'l connected to the enlargement M3 on the sideof the supporting ring is of the housing 28 of the-objective lens .(not shown). Adjacent tothe boss [6 on the shaft l5 there is positioned the plate 2i having the bosses 22 and 23 securedto the shaft 15. The plate 21 in the present embodi ment has at one end the support 24 to which is pivotally connected the bracket 25 formed at the end of the rod 26 extending through the. sleeve 2'! pivotally'mounted on the bracket 28 of the deflector or mirror 29. Secured'to the other end of the plate 2! there is provided the plate so on whichthere is mounted the reflector 3i. This ,is preferably spaced from the plate 30 by a cushion32. The reflector 3| preferably forms a concave mirror or deflecting face 33, preferably parabolic or so approaching a parabola that a cone of light conforming to the dash and dot lines as may be formed witha lamp 35 having a light center at 36. The lamp in-the presentinstance extends throughanopening 3? formed between the reflector 3i and the plate ts'having the lamp socket 33' secured to the wire conduit 39 which in turn'is secured in the bracket 40 supported on theplate 2|. In the present instance, as shown in Fig. l, the conductors-4i and 42 for the lamp socket 38 extend through the conduit 39. 'The reflector '31 is out in half'to ceive the light rays and produce the ultimate picture when the printed matter on a tape, such as the tape 44, passes over a reflector 45 after it leaves the printing position on the platen of an electric typewriter. In other words, the light rays from the lamp 35 will be deflected by the reflector 3| through the tape 44 onto the first surface mirror or reflector 45 and by the reflector 45 directed back through the tape and then through the objective lens formed in the housing 20 and from the objective lens in the housing 26 onto the mirror 29 and by the mirror 29 be deflected onto the front face ofrthe screen 43. The dash and dot lines 34 are indicative of the path of the light rays from the lamp and reflector 3| through the tape 44, reflector 45, objective lens in the housing 26, deflector 29 and front face of the screen 43. When the light passes through the tape 44 onto the reflector 45 it forms an image which is in turn reflected back through the tape 44 and a second image superimposed upon the first image when passing through the tape 44, thereby increasing the contrast between the image and its immediate environment, in turn to emphasize the definition of the image in the interest of legibility. The mirror 45 is bevelled at its lower edge preferably on a radius to conform to the radius of the platen 46 as at I45 and thus permit very close mounting of the mirror 45 relative to the platen 46.

Preferably the tape 44 is composed of some translucent or transparent material such as cellophane, glassine paper and the like. The platen 46 is indicative of the platen of an elec tric typewriter having a tape supply roll 41, the paper of which passes up over a guide bar in the upper end of the frame 48 and then down around the platen 46 into the printing position to receive the impressions from the type bars 49 and then across the reflector 45 in the present instance secured to the frame 50 of the electric typewriter, and then after leaving the reflector 45 across the guide bar mounted in the upper end of the arms 52 formed at the rear end of the extensions 53 of the frame portion 54 of the electric typewriter and from the guide bar 5| down into engagement with and around the guide bar 55 at the end of the lever 56 fulcrumed at 51 in the support 58 and having a pin 59 in engagement with the spring 60 normally raised but in position to be deflected downwardly to depress the pin 6| of the microswitch 62 to shut off the current to the motor 63 through the conductors :64 and 65. The motor 63 in the present instance has a sheave carrying the belt 66 which in turn passes around the sheave 61 secured to the shaft of the takeup roller 68, the shaft of which is journalled in the upper end of the support 58. In other words, in the conventional way when the electric typewriter 69 comes to rest, that is, when no message is being transmitted and the type bars 49 are at rest, the motor 63 will continue to acutate the tape roller 68 until the loop formed by the guide rod 55 is diminished thereby to raise the arm 56, in turn to deflect the spring 60 and depress the projection 6| to shut oif the current to the motor 63. In turn, as soon as the electric typewriter 69 again starts operating, and feeding tape into projection 6| of the microswitch 62 to enable the projection 6| to return to its normal contact forming position.

Excellent results have been achieved when" the reflector 3| is composed of glass and has a silvered rear. mirror face and when the reflector 45 is composed of a highly polished reflecting metal face or first surface glass mirror, al though obviously the reflecting face of the re flector 3| may be composed of a highly polished metal reflecting face or of a glass having a rear silvered mirror forming face, without departing from the general spirit of the invention.

The embodiment shown in Fig. 4 differs from the embodiment shown in Fig. 1 primarily in showing a rear projection screen and the adaptation of this optical system to a rear projection screen 16. With such rear projection screen 16, however, an additional mirror is required, such for instance as the mirror 1|, in which case the light rays after passing through the objective lens in the housing 12 first strike the deflector T3, are deflected by it onto the deflector 1|, and in turn deflected by the deflector onto the rear face of the rear projection screen 10.

While for most purposes the embodiments shown in Figs. 5 and 6' may be substituted for the embodiment shown in Fig. 1, under certain circumstances the embodiments shown in Figs. 5 and 6 may be preferred. As an instance, the spherical reflectors are cheaper and readily available and so for this reason the embodiment illustrated in Fig. 5 using a spherical reflector, such as the reflector |3|, might be preferred.

In turn when the available space between the standard I64 and the platen I46 is limited, the embodiment shown in Fig. 6 may be preferred where instead of the parabolic reflector 3| of Fig. 1, an elliptical reflector 23| is used.

From the foregoing it will appear that the dash and dot line 340 in Fig. 2 coincides with the axis of the parabolic mirror 3| and that the light center 36 is positioned on said axis 340 but outwardly of the focal point of the mirror 3|; that the dash and dot line |34 in Fig. 5 deflnes the axis of the spherical mirror |3| and that the light center I36 is similarly disposed outwardly of the focal point of the spherical mirror |3| and that the dash and dot line 234 of Fig. 6 is in alinement with the axis of the elliptical mirror 23| and that the light center 236 coincides with the focal point of the elliptical mirror 23|. With all of these three embodiments it will be seen that the edge defining the half section of the mirrors 3|, |3| and 23| is disposed adjacent the path of the light beam from the reflector 45 to the objective lens 26, and that the angle of incidence of the light rays passing to the reflector 45 and the angle of reflection of the light rays passing from the reflector 45 to the objective lens 20 are maintained as acute as possible to prevent distortion of the image. This objective is produced when the concave reflector, to wit, the reflector 3| of Fig. 2, reflector 3| of Fig. 5, and the reflector 23| of Fig. 6, is cut in half with its half section adjacent the path of the reflected light rays from the reflector 45 to the objective lens 20 and the concave reflector 3|, I31 and 23! is disposed in the region intermediate the reflector 45 and the objective lens 20. It is of course obvious that in all of the three aforesaid embodiments the tape 44 crossing the reflector 45 is transparent and that consequently the angle of incidence of the light rays passing from the concave reflector 3|, [3! or 231 to the plane reflector 45 and tape 44 must equal the angle of reflection of the light rays passing from the reflector 45" through the tape 44 to the objective lens 20.

arcuate surface that is interrupted at its bases or ends and thus does not form a complete arcuate enclosure.

It is obvious that various changes and modifications may be made to the details of construction Without departing from the general spirit of the invention as set forth in the appended claims.

I' claim:

1. The optical system for projecting the images of impressions produced by a typewriter on a transparent light transmitting tape as they are made characterized by a plane first surface reflector extending from the platen of the typewriter to receive and support the tape after the impressions have been made thereon, a source of light, an objective lens, a half section of a full concave reflector in the region intermediate said lens and said first surface reflector cooperating with said source of light and said flrstf surface reflector to converge the light rays through the tape onto said first surface reflector passing to said objective lens, a projection screen, and deflecting means intermediate said objective lens and said projection screen to pick up the light rays from said objective lens and direct them onto said projection screen, said objective lens, screen, and concave reflector being adjustable relative to one another except that the light center of said source of light will remain at all times on the axis of the concave reflector, and that the edge of the concave reflector defining the half section of the same is disposed adjacent to the light rays passing from the first reflector to the objective lens, and that the source of light is disposed in the region intermediate said first surface reflector and said objective lens.

2. The combination as set forth in claim 1 in which said first surface reflector is a plane surfaced mirror and said concave reflector is parabolic in form.

3. The combination as set forth in claim 1 in which said first surface reflector is a plane surfaced mirror and said concave reflector is spherical in form.

4. The combination as set forth in claim 1 in which said first surface reflector is a plane surfaced mirror and said concave reflector is elliptical in form.

PAUL K. T. HARTMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,081,922 Balderston Dec. 16, 1913 1,344,379 Chidester June 22, 1920 1,920,473 Maury et a1. Aug. 1, 1933 2,098,941 Blohm Nov. 16, 1937 2,108,056 Eitzen Feb. 15, 1938 FOREIGN PATENTS Number Country Date 639,555 France Mar. 13, 1928 412,579 Great Britain June 28, 1934 585,868 Great Britain Feb. 27, 1947 

